Method and apparatus for electrically heating and forming metal bodies



Aprll 2, 1946. 5 w s METHOD AND APPARATUS FOR ELEGTRICALLY HEATING AND FORMING METAL BODIES Flled July 5, 1944 Sven Wesfiz'n INVENTOR 8W 5 ATTORNEY.

Patented AP METHOD AND APPARATUS FDR ELECTRI- CALLY HEATING AND FORMING METAL BODIES Sven Westin, West Allis, Wis., assignor to A. 0.

Smith Corporation, Milwaukee, Wis.,

tion of New York a corpora- Application July 3, 1944, Serial No. 543,231

9 Claims.

This invention relates to a method and ap paratus for electrically heating and forming metal bodies.

This application constitutes a continuation in part of applicants co-pending application Serial No. 463,957, filed October '30, 1942, for'Method and apparatus for electrically forming pipe, now Patent No. 2,374,794, dated May 1, 1945.

The principal object of the invention is to provide a method of electrically heating and forming circumferential or circular corrugation or shapes in tubular or bar work pieces.

Another object is to provide an apparatus employing electrode die for engaging a work piece and in which the dies are movable radially during the forming operation to effect shaping of the piece.

An embodiment of the invention is illustrated in the accompanying drawing in which:

Figure 1 is an axial section through an apparatus for forming a corrugation in a tubular work piece and showing a cylindrical tube positioned therein for forming;

Fig. 2 is a similar section showing the forming operation;

Fig. 3 is a similar section showing the withdrawal of the dies and release of the formed piece;

Fig. 4 is a transverse section taken online 4-4 of Fig. 3 and showing the apparatus in end ele v vation; and

Fig. 5 is a side elevation of the apparatus of Fig. 1 showing the addition thereto of a second chuck for effecting thickening or thinning of the work piece.

The apparatus comprises in general a rotary chuck I for rotatably supporting the tubular work piece 2 and for moving the same into and out of forming position, and' the radially movable forming die electrodes 3 for forming the work piece.

The chuck I is mounted on a longitudinally slidable pedestal 4 and rotated by a motor 5 and reduction gearing 6 also carried by the pedestal. A hydraulic cylinder 1 is disposed to move the pedestal 4 longitudinally to locate the Work piece in the forming dies 3.

The forming apparatus comprises two or more electrode dies 3, opposed to each other radially about the circumference of the work piece and having their di surfaces shaped to provide the desired contour for the final corrugation 8 in the work piece.

The dies 3 are mounted for radial movement toward and away from each other under the control of hydraulic cylinders 9 or of some mechanical power mechanism. They are adapted to move inwardly upon the work piece to form the same.

The dies 3 are circumferentially spaced apart and constitute opposite electrodes of a supply circuit II) for supplying electricity to the blank as the latter rotates in contact with them. For this purpose the leads of circuit I0 connect the dies to the secondary of a transformer I I. Leads I2 connect the primary of the transformer II .to source I3 of electric current.

In operation, the tubular blank 2 is gripped at one end by the chuck I and then moved longitudinallyinto the forming apparatus until the dies 3 encircle the desired location, for corrugation 8. Then the chuck I is rotated, thereby rotating the blank, and the heating current being applied to the die electrodes 3 by transformer II, the dies 3 are moved radially inwardly to contact and press against the surface of the rotating blank. The electricity being supplied to the dies passes through the circumferential portions of the blank between the die electrodes and heats only the portion to be formed.

Heating the circumferential portion of the blank contacted by the dies softens it and allows it to yield to the radial pressure of the dies and the latter move progressively inwardly until the corrugation 8 or other shape is completed in the blank.

Upon completion of the corrugation 8 or other forming operation, the heating current is discontinued and the dies 3 arewithdrawn radially outward from the blank 2. The formed blank may then be moved longitudinally to a new location for forming a corrugation therein adjacent to the first corrugation, or it may be removed from the forming apparatus.

In the forming ofdiifer'ent shape it is possible to provide for a combined longitudinal feed of the blank and radial feed of the electrode dies during the forming operation, in which case various tapers may be provided in the blank.

Where it is desired to control the thickness of the blank in the region of forming, it is possible to apply either longitudinal compression forces or longitudinal tensile forces to the blank durin the forming operation.

This may best be accomplished, asshown in Fig. 5, by providing an additional rotary end chuck I4 to grip the leading end of the blank 2. The chuck I4 is mounted on a slide I5 along which it may be moved by hydraulic cylinder I6. The chuck may be rotated by a motor I1 and reduction gearing I8.

In operation the chucks I and I4 should be rotated at the same speed and they may be moved toward one another during the forming operation to facilitate or compensate for the endwise contraction of the blank and maintain or increase its thickness in the formed region. If desired the chucks may-be held against longitudinal movement or even moved apart during the forming operation for the purpose of thinning the blank in the region of forming. Any desired combination of end movement can be employed with the radial forming to produce shapes of various kinds.

Various embodiments of the invention may be employed within the scope of the accompanying claims.

I claim:

1. The method of reducing and forming a circular blank for a portion of its length, comprising disposing the same in a restricted die opening constituted of a plurality of spaced die electrodes supplying heating current to the blank from one of said electrodes to another while the electrodes and blank are relatively rotated under conditions of radial pressure therebetween to effect a reduction in diameter and forming of the blank, and thereafter separating the electrodes and removing the blank therefrom.

2. The method of reducing andforming a circular blank for a portion of its length, comprising disposing the same in a restricted die open ing constituted of a plurality of radially movable spaced die electrodes for supplying heating current and forming pressure to the blank, relatively rotating the blank in the die opening, and moving the dies radially inward into pressure contact with the blankto effect simultaneous heating of the blank by the passage of current therethrough from one of said electrodes to an other andforming of the blank.

3. The method of reducing and forming a circular blank for a portion of its length, comprising disposing the same in a restricted die opening constituted of a plurality of radially movable spaced die electrodes for supplying heating current and forming pressure to the blank, relatively rotating the'blank in the die opening, moving the dies radially inward into pressure contact with the blank to effect simultaneous heating and forming of the same, and moving the blank longitudinally relative to the dies during the forming operation to effect tapering of the blank.

4. The method of reducing and forming a cylindrical blank, comprising rotating the blank, and .moving a plurality of circumferentially spaced electrode iorming dies radially inward thereagainst, said dies supplying heating current flowing circumferentially through the blank from one of said dies to another in the region of forming of the blank.

'5. The method of reducing and forming a cylindrical blank, comprising rotating the blank, moving a plurality of circumferentially spaced electrode forming dies radially inward thereagainst, said dies supplying heating current flowing circumferentially through the blank in the region of forming thereof, and applying differential longitudinal forces to the opposite ends of the blank to facilitate the forming operation.

6. The method of reducing and forming a cylindrical tubular blank, comprising rotating the blank, moving a plurality of circumferentially spaced electrode forming dies radially thereagainst, said dies supplying heating current flowing circumferentially through the blank in the region of forming thereof, and applying difiertial longitudinal forces to the opposite ends of theblank to control the wall thickness thereof in the forming region.

7. In apparatus for electric forming operations, aplurality of circumferentially spaced electrode dies arranged in a circle to receive a circular blank to be formed, means to move said dies radially into pressure contact with the work blank, means to rotate the blank in said dies, and means to supply heating current to the dies to effect resistance heating of the blank by the flow of current through the blank from one of said dies to another in the circumferential path of the dies thereagainst.

8. In apparatus for electric forming operations, a plurality of circumferentially spaced electrode dies arranged in a circle to receive a circular blank to be formed, means'to move said dies radially into pressure contact with the work blank, means to rotate the blank in said dies, means to supply heating current to the dies to effect resistance heating of the blank in the.

tions, a plurality of circumferentially spaced electrode dies arranged in a circle to receive a cylindrical blank to be formed, means to move said dies radially into pressure contact with the work blank, means to rotate the blank insaid dies, means to supply heating current to the dies to efieet resistance heating of the blank in the circumferential path of the dies thereagainst, a pair of rotary chucks for gripping the blank at opposite ends thereof, and means to move said chucks longitudinally of the dies and relatively to one another.

SVEN WESTIN. 

